Photographic printing system for channelized multiple trace records



Nov. 28, 1961 J. D. ElSLER ET AL PHOTOGRAPHIC PRINTING SYSTEM FORCHANNELIZED MULTIPLE TRACE RECORDS 5 Sheets-Sheet 1 Filed Nov. 29, 195'?FIG.I

mvrsmonsz JOSEPH D-EISLER CHARLES E HADLEY HAROLD M. LANG DANIEL 8%ERMANBY mronnv Nov. 28, 1961 J. D. EISLER ET AL 3,011,145

PHOTOGRAPHIC PRINTING SYSTEM FOR CHANNELIZED MULTIPLE TRACE RECORDSFiled Nov. 29, 1957 Sheets-Sheet 2 40 40 3| 2o I I I I l I I I I I I I II 24 FIG.6

INVENTORSZ JOSEPH D. EISLER CHARLES F. HADLEY HAROLD M. LANG DANIELSILVERMAN M WATT RNEY Nov. 28, 1961 J. D. EISLER ET AL 3,011,145

PHOTOGRAPHIC PRINTING SYSTEM FOR CHANNELIZED MULTIPLE TRACE RECORDSFiled Nov. 29, 1957 5 Sheets-Sheet s JOSEPH D. EISLER CHARLES F. 'HADLEYHAROLD M. LANG DANIEL SILVERMAN IN V EN TORS- ATTORNEY Nov. 28, 1961 J.o. EISLER ET AL 3,011,145

PHOTOGRAPHIC PRINTING SYSTEM FOR CHANNELIZED MULTIPLE TRACE RECORDSFiled Nov. 29, 1957 5 Sheets-Sheet 4 s E 3| O: 3 \\\\T28 27 25 3 FIG. 4

30 FIG.?

INVENTORS JOSEPH D. EISLER CHARLES F. HADLEY HAROLD M. LANG H8 DANIELSILVERMAN Nov. 28, 1961 J. D. EISLER ETAL 3,011,145

PHOTOGRAPHIC PRINTING SYSTEM FOR CHANNELIZED MULTIPLE TRACE RECORDSFiled Nov. 29, 1957 5 Sheets-Sheet 5 FIG. l2 II T l3! E I30 31 GD AD,

9 I TIME- ADO A0,, T1ME I;-'7-'-7' 77W so INVENTORS:

I32 JOSEPH 0. EISLER FIGJB CHARLES E HADLEY HAROLD M. LANG DANIELSILVERMAN United States Patent 3,011,145 PHOTOGRAPHIC PRINTING SYSTEMFOR CHAN- NELHZED MULTIPLE TRACE RECORDS Joseph I). Eisler, Charles F.Hadley, Harold M. Lang,

and Daniel Silver-man, all of Tulsa, Okla, assignors to Pan AmericanPetroleum Corporation, Tulsa, Okla,

a corporation of Delaware Filed Nov. 29, 1957, Ser. No. 699,753 7Claims. (Cl. 340-15) This invention relates to seismic geophysicalsurveying and is directed particularly to the display of seismicgeophysical data. More specifically, the invention is directed to asystem for making records suitable for use in crosssection displays inchannelized-trace form by compensating or correcting channelized-tracefield or playback records for both fixed and varying trace-timedifferences. If desired, the records can be corrected also fornonlinearity of the relation between trace times and depths of geologicboundaries.

The term channelized is used herein in the sense that the various tracesof a record are confined to individual parallel bands or stripes thatextend along the record without lateral overlapping. Variable-densitytraces are an example of this, and constitute the preferred form ofrecording for use of this invention, but it is obviously not necessarilylimited thereto.

As a result of many years of intensive seismic geophysical surveying, atremendous amount of data has been accumulated covering many geophysicalregions. At times, not all of the recorded information is being utilizedsimply because of a lack of skilled interpreting per-sonnel. As an aidin handling larger volumes of data and to assist less skilled personnelto perform valuable interpretations, attention has been directed to thedisplay of the data in various forms of record cross-sections; Thus, allof the records obtained along a given line of shot points may be placedside by side in a display to show trends which continue across all ofthe records or only for a few of the traces.

In studying such cross-sections it is highly advantageous lice simplerin some of its mechanical aspects, requires more time.

It is accordingly a primary object of our invention to provide a noveland improved transcribing system for op tically correcting a number ofchannelized data traces simultaneously. A further object is to providesuch a system which is rapid in operation and flexible in adapting tovarious arrangements of spreads and shot holes, and wherein all of thecorrections required for a given multi-trace record are applied at onetime. Still further objects of the invention are to provide such asystem with an easily changed time-to-depth conversion means, allwithout undue mechanical complexity. Other and further objects, uses,and advantages will become apparent as the description proceeds.

Briefly described, the system is one wherein a paralleltracephotographic field or playback'record it is desired to correct andtranscribe is transported lengthwise across a beam of parallel lightrays. A plurality of slit-carrying means extending across the beam andmovable in the direction of motion of the field record define the pointsalong the various traces which are simultaneously scanned. The lightrays passing through these slits, as modified by the correspondingrespective record traces, are projected toward a'lengthwise-movingunexposed film strip along a single straight line transverse to thestrip. During the I transcribing of each record, the slit-carryingmembers and not to have to consider the eifects of weathering,elevation,

and shot-depth variations along the profile line and of normal move-outdue to differing distances between the shot point and the variousseismometers. The former are causes of fixed, and the latter is thecause of varying traces time differences for reflected events on arecord. With in which drawings:

these causes of time variations for a given event on dif ferent tracesand different records removed, it often becomes much easier to observesignificant 'thoughobscure line-ups and relationships on the records. 7

The presentation of the traces in variable-density form is of especialadvantage, as the light and dark patterns of events which alignthemselves resemble in some degree the subsurface Stratification beingstudied. It'is also of considerable advantage in perceiving thegeological 'significance of the cross-sections to have the various partsrelated linearly with depth, rather than compressed at increasing depthsas occurs in records made with a uniform time scale. V

In preparing cross-section displaysfparticularly of the variable-densitytype, usingrecords corrected for tracetime diiferences, there are twogeneral ways of proceeding. One is to determine and apply at'one'timeall of the corrections for both'fixed and varying trace-time differencesto all of the traces forming one record. .The

other is to apply the necessary corrections to the record one trace at atime, readjusting the apparatus and'repeating the corrections for eachsubsequent trace. The first procedure, while requiring morecomplex-mechanism, obviously accomplishes the desired corrections in aminimum amount of time. "The second procedure, vvhile slits are movedlengthwise relative to each other by an appropriate adjustable mechanismby amounts adapted to compensate for the normal move-out of the recordedseismic signals. Additionally, the beam from each slit may be deflectedso that its final position of incidence on the unexposed film isdisplaced from the transverse straight line by a proper amount tocompensate for the ordinaryfixed trace-time differences. Preferably, butnot necessarily, the field record and the unexposedfilm are transportedalong parallel paths or tracks which are circular and concentric.

Ordinarily, field records have a linear time scale; When it is desiredto convert from such a scale/to one that is linear in depth inaccordance with a given nonlinear time-depth curve, the drivingconnection between the field record and unexposed film travel paths isvaried in length by suitable means such as a cam arrangement. This willbe better understood by reference to the accompanying drawings forming apart 'of this application,

- FIGURE I is a highly diagrammatic over-all of the' apparatus formingthe invention; 1.

FIGURES 2 and 3 are respectively assembled and exploded cross-sectionviews through part of the apparatus;

FIGURES 4 and 5 are cross-section views through-the.

optical system respectively at right angles at each other;

FIGURE 6' is an elevation rection mechanism; i FIGURES .7, 8v and 9 areviewsof a portion'of the apparatus in FIGURE 6 in'.variousope'ratingpositions;

FIGURE 10 is a cross-section view through themeans; forintroducing'static corrections; s 1 a FIGURE 11' is an elevation view.of part of. the ap paratus ofFIGURE: 10; j V

FIGURE'IZ shows the use of an elevation andweather-V ing-card adjustingmechanismfor making staticcorrections;

FIGURE 1'4-isf a detailed view of thelinlcage' iiijsm for making thisconversion.

" Referri g now ,to'these drawings indetail, andparticuplan view view ofthe dynamic cor- FIGURE 13 is'agraphrshowing therelationshipof thetime-to-depthJcurve to the means foriiconver-ting from a linear time to.a linear. depth scale;'andi mecha arm 24 which holds the film by meansof a clamp 22 V and supports the free end thereof on a reel 23. It willbe understood that the film 20 is one which bears thereon a. number ofparallel traces of seismic data in channelized, preferablyvariable-intensity, form. In order to prepare a corrected copy of thefilm 20 for assembly into a crosssection display, light from anessentially point source 26 is collimated by lenses 27 and 28 into abeam of parallel rays of substantial area. Some of these parallel rayspass through the slit 39 of a slit-carrying member 29 closely adjacenteach of the parallel traces of the film 20, there being one such memberand slit for each trace, the light emerging from each slit passingthrough the corresponding film trace and being modulated according tothe density thereof, then passing through a cylindrical lens 31 whichprojects or focuses the rays passing through the various slits 30 andthe different traces onto the surface of an inner unexposed film 40along essentially a single straight transverse line. For the purpose ofintroducing fixed trace-time corrections, however, each slitdefined beamfrom the lens 31 is preferably deflected through approximately twoopposite right angles by a fixed mirror 32 and a pivoted mirror 33pivoted at the point 34, passing thence to the face of film 46. Theexact angular deflection of each slit-transmitted beam produced by eachcorresponding mirror 33 is determined by a lever arm 35 positioned bythe edge of a weathering card 36 placed in a holder 37 of appropriatelocation and form.

While many details of the actual construction have been omitted fromFIGURE 1 to avoid confusion, it will be understood that the unexposedfilm 40 is entirely surrounded by a light-excluding housing 41preventing stray light from striking the film. Unexposed film is carriedon a reel 43 inside of the drum 66 supporting the film 40 and passesover a sprocket 46 actuating a counter 44, around the drum and back to atake-up reel 42 which can be turned from outside the drum by a crank 45.The uncorrected field record 20 is normally stored on a stationary reel48, from which it passes an index mark 49 and around a pulley means 47before being drawn around the outer circular path closeto the slits 30,The relative positions of the slits 30 on the various slit-carrying bars29 within the parallel light beam area determine the points on thevarious traces of the film 20 which are simultaneously scanned andtransmitted through the lens 31 for focusing thereby on the receivingfilm 40.

The construction and operation of the film-transporting means will bemore easily understood frornFIGURES 2 and 3, particularly the latterfigure which is an exploded view of the apparatus of FIGURE '2. Theentire assembly is supported upon a base 55, the rotatable portions ofthe apparatus being mounted on a vertical shaft or spindle 56 securelyfastened to the base 55. The field film transport mechanism comprises ahub member 57 mounted onbearings on the shaft 56, to which hub isattached a disc 58 provided with an outer cylindrical rim 59. A bevelgear 60 transfers to apinion gear 61 on the end of shaft 52 extendingradially outward from shaft 56 a rotation proportional to the movementof the rim 59. i

Also mounted to theshaft 56 is a second hub. member 65 carrying theinner film-carrying drum 66, a'regis'tering pin 67 on the drum 66fitting in a hole '68'of-thehub 65 so as to orient the two members in afixed relation.

Between the rotatable upper drum 66 and the lower rotatable rim 59 is astationary cylindrical shield member '70 closely fitting the outsideofdrum 66 and supported from the base 55 by a plurality of overheadcurved arms 71, An annular disc 72 attachedtothelbase of the shield 70'fitsclose tobut does not contact the disc 58, and rim 59. The shield'70 cooperates with aTdown-turned flange operation with the solid disc58 and the upwardly extending portion of cylindrical rim 59 similarlyform a trap for light which might enter from below. An aperture 74 inthe shield past which the film 40 is carried by drum 66 admits the lightbeams which form the exposed tracks on the film 40. Motive power tooperate the apparatus is applied to the lower inside portion of rim 59by a constant-speed electric motor 77 attached to the base 55 anddriving a rubber roller 78 in firm frictional contact with the rim 59.Limit switches, not shown but of any wellknown type, may be provided tostop the motor 77 from driving the rim 59 too far in either direction ofits rotation.

To the outside of the rim 59 are attached the field film take-up reel 23and the film-moving arm 24 carrying the clamping means 22. Thus, as therim 59 is rotated by the motor 77, the arm 24- draws the film 20 aroundthe outer circular path 21 past the stationary optical system and themovable scanning slits 30.

Although the rim member 59 is driven by the motor 77 in a positivemanner, the drum 66 on the hub member 65 may rotate with respect to rim59. For making corrected records to a linear time scale or whatever timescale exists on the uncorrected record 20, it is necessary only toinsert a fixed connecting link, not shown, between the disc 58 and thedrum-carrying hub 65. However, if it is desired that therecord-receiving film strip 40 be moved in a fashion which varieslinearly with depth rather than time, some variable linkage between thedisc 58 and the hub member 65 is necessary. To accomplish this, thereisfastened to the underside of disc 58 at its outer edge a frame member 81carrying a pair of vertical guide rods 82 along which may travel acarriage 83. On a shaft extending from the carriage 83 is a roller 84and a pulley member 85, there being a corresponding pulley member 86 infixed position on the lower end of frame 81. Attached to the frame 81 atthe point 86 is a cord or flexible wire 87 which extends around themovable pulley and the fixed pulley'86. The roller 84 is adapted tocontact the edge of a cam or template 9% of sheet metal bent in a circleand held in a circular channel 89 fastened to the base 55, the edge oftemplate 90 being contoured in accordance with the time-depth curve in amanner which will be more fully described below. The channel 89 holdsthe template 90 in a cylindrical form so that, as the disc 58 rotatescarrying the frame 81 and roller 84 in a circle, the roller 84 remainsin contact with the edge of the template 90.

The flexible cord or Wire 87 passes through the disc'58 via a narrowopening 91 designed to prevent light leakage, being guided therethroughby pulleys 92 and 93 mounted on either side of the disc. On the upperside of disc 58 the cord 87 passes one or more times around the outsideof a drum 95 fixed to the bottom portion of the, hub 65 and is attachedto one end of a spring 96. The other. end of spring 96 is connected to apost 97 attached to the'disc 58. I

The manner of operation of this varying interconnection between the disc58 and drum 95 can be better understood from FIGURE 14. Thus, as theroller 84 and carriage 83 moves the pulley 85 up or down relative to theanchor point 80 andpulley 86-, which are transported along a circleparallel to base 55 in accordance with the'positionof the edge of mask96, more or less of the fixed length of the cord 87 is included betweenthe anchor point 80 and the fixed pulley 86. .This accordingly displacesthe end of the cord 87 attached to the spring 96, changing its length,and producing a corre- 73 onthe upperedgefof the drum 66 to prevent likeleakage and fogging of the film 40 which is positioned on the outside ofthe drum 66. The annular disc 72 in cosponding rotation of the drum 95.Thus, by properly shaping the edge of the template 90, the drum 95 andthe film 40 carried by drum 66-mounted thereon can be moved at eitherthe same-or a greater or lesser speed tlh7an the speed of rotation ofthe disc'SS by the motor g The functioning of the opticalfsystem isshown more clearly in FIGURES 4 and 5. 'Thus, the light source 26 andthe collimating lenses 27 and 28 are contained in a housing 25 which ispositioned closely adjacent the slit-carrying members 29. The view ofFIGURE 4 is a cross-sectional view similar to FIGURE 1 and demonstrateshow the cylindrical lens 31 brings the different portions of theparallel beam transmitted by different ones of the slits 30 through thefilm 20 to focal points lying along a single straight line extendingtransversely across the film 40. As the function and effect of themirrors 33 and 34 are independent of these portions of the opticalsystem, they have been omitted in these figures.

As appears in the cross-section view of FIGURE 5, which is takenperpendicular to that of FIGURE 4 and wherein the motion of the films 20and 40 is perpendicular to the plane of the figure, the cylindrical lens31 does not affect the vertical positions ofthe parallel-beam portionstransmitted by the slits 30, so that the various tracks on the film 20are transmitted by the lens 31 to the film 40 without altering theirvertical separations. Thus, the positions and spacing of the individualtracks on the film 40 are the same as onthe film 20, but the relativetimes of occurrence of given events on the different tracks of the film20 can be altered on the film 40 by differently positioning the variousslit-carrying members 29 in the manner shown in FIGURE 4.

The detailed construction of the normal move-out correcting mechanism 51is best shown in FIGURE 6. By normal move-ou is meant those trace-timedifferences which are due solely to the location of differentseismometers at different distances from a shot point, and thecorrection, which varies with time along the record, preferably consistsof shifting all events to the times at which they would have beenrecorded with the seismometer at the shot point. Mounted on the base 55are a pair of vertical guide rods 101 and 102 along which can slide apair of tubular guides 1133 and 1134 which with their end members 1&5and 1% form a rigid movable frame. A locking lever 107 on the framemember 166 looks the frame in any desired vertical position along theguides 1G1 and 102. Mounted so as to slide vertically along the tubularguides 103 and 104 is a carriage member 110 adapted to be locked at anydesired position on these guides by the lever 111. Attached to thecarriage 111i is a gear box 112 carrying the cam 113 which bears againsta cam follower 114 at one end of a lever 115, pivotedat point 115 to anarm 121 supported from the carriage 1111.

Bearing against the side of lever 115 is a push rod 117 attached at itsother end to a fork 118 and guided for lengthwise movement by a guide119 attachedto the frame member 106. The ends of fork 118 are adapted topress against the ends of .a plurality of leaf springs 12% attached attheir centers to the guide member 119. The face of the leaf springs 120is in contact with the ends of the slit-carrying rods 29,.

The cam 113 is movable in accordance with the rotation of the disc 58through the shaft 52 driving gearing 124 which in turn rotates a splinedrod 125 engaging:the gearing in box 112 to which thecam 113 isconnected. Thus, a positive driving connection is maintained between thefilm 20 moved by the disc 58 and the cam 113, regardless of the verticalpositioning of the carriage 110 on guides 103 and 104 or of the tubularframe along the guides 101 and 102.

The operation of this mechanism is shown in FIGURES 6, 7, 8, and 9. Thefilm 20 is preferably moved in the opposite direction to that when itwas recorded, by aligning the time break defining zero time with theindex mark 49. Thus, starting with the slits 313* aligned'as in FIG- URE6, and with the array of slit-carrying rods 29 centered with respect tothe leaf spring 120, the move-out correction corresponds to thereflection from a very deep horizon for which there is nearly zerotrace-time difference due to the normal move-out effect between'thecenter distances between the shot point and the seismometers,

ofth e spread and the seismometers farthest from the shot point.- Forreflections from increasingly shallower horizons the corrections becomelarger and the spring 120 is deformed, moving the slit rods 29 as shownin FIGURE 7. In this figure the outer guide rods 29 of the arraycorrespond to the seismometer positions farthest from the shot point,the entire array corresponding to what is normally called a splitspread.

To accommodate another spread configuration such'as an end-offsetspread, in which the shot point is displaced from 'one end of the spreadrather than opposite its center,the configurations of the spring 120 andthe array of slit rods 29 are as shown in FIGURES 8 and 9'. Thus, withlever 1117 released, the'entire frame 103, 104, and 106 is movedverticallywith respect to the positions of the ends of the slit rods 29until the center of the spring 120, corresponding to the shot pointposition, is-opposite the slit rod 29of that seismometer of the spreadclosest to'the shot point. For zero correction of reflections from greatdepths the slit rods 29 are positioned as in FIGURE 8, while for thesubstantial amount of move-out correction needed for reflections fromshallow depths the positions of the rods and'deflections of the spring120 are as shown FIGURE 9; i

Releasing'the locking lever 111 and shifting the position of thecarriage along'the tubular members 103 and 164 comprises the spreadlength adjustment. By this movement the point of contact of the rod 117is varied along the-edge ofthe lever 115. Thus, with the contact pointat the lowest position a minimum fractional part of the motion of thecam follower 114 is transmitted to the fork 118 and springs120,;whilewith the upper end of lever contaeting the end of rod 117 themaximum movement is imparted to the rod 117. This maximum 7 movement ismade suificient to correctfor the move-out of the seismometers which areat the maximumdistances from the shotjpointever likely to be employed.Intermediate positions of the contact between rod117 and lever-;115 suchas that shown in FIGURE 6 provide the move-out correctionforintermediate distances of the end seismometer of various spreads. Theactual positions for various spread lengths, or maximum seismometer distances are most conveniently indicated by a scale marked on the face oflever 115. I

As the flexing of the leaf spring in the manner shown by pressure atitsends while supported in the cen-1 terresults in points alongthelength of the spring lying on various paraboliccurves, the endwisemovement of any one of the slit rods 29 is proportional to the square ofits distance from the center of spring 120. By design ing-the outline ofcam 113 -to correspond to the-inverse of the product of depth andvelocity, utilizing the relationship between time and depth it is.desired to use for a given prospecting area, this entire mechanismapproxi mates the expression 7 H v V 4DV' V where- X is the distancewfromTthe shot point to any seis- 1 mm; nn t m D3 1 t e t of h rsfl a nahorizon, and V is the average velocityfrom the surface ofthe groundto'that depth. As is well known, th is expression-is; to 'a closeapproximation, the necessary move out correction for thertracerrecordedby a seismometer at distance X from the shot point in any spread Thus,with adjustmentsprovided in this relatively simple manner both for thetotal length of thespread and its :location with respect to theshotpoint, it' is apparent that a high degree; of versatility ispresent; i

Besides the dynamic correction for move-outmdue to it also necessary to:be ableto fapply fixed valueslof correction to the traces made byvariousseismometers of aspreadvto'cornpensate for .variations ofweathering ic n ne h pr ele a n t n a u a seismometer with respect tothe shot point, depth of the shot in the shot hole, or travel times fromthe various seismometers and the shot to a reference datum plane. InFIGURES 10, l1, and 12 is shown in more detail the arrangement of themirrors 33 and 32 of FIGURE 1 for accomplishing this result. Thus, allof the slit-defined beams from lens 31 are bent through approximately aright angle by the fixed mirror 32 and impinge on a plurality ofindividual mirrors 33 pivoting on the shaft 34. Each of the mirrors 33intercepts one of the beams and is provided with arm 35 projectingthrough a slot in the wall of the light-tight housing 41 into contactwith the edge of a weathering card 36 in a holder 37. A tension spring38 holds the end of each arm 35 against its corresponding portion of theweathering card 36, while a slide 39 attached to the arm 35 preventslight leakage through the slot into the housing.

As was stated and appears most clearly in FIGURE 11, each small mirror33 is positioned to intercept a different one of the beams from thescanning slits 30. Thus, each beam is reflected through a differentangle depending on the angular setting of the corresponding mirror 33 inaccordance with the position of the end of the corresponding arm 35against the weathering card 36. This card may be of the form shown inFIGURE 12 where the edge has been cut in an irregular fashion dependingon the correction pattern desired by a punching or cutting means of anyknown conventional type, so that the end of each lever 35 is accuratelypositioned for the total fixed correction desired. It will be understoodthat this will include all fixed corrections required by the profilerecord, and thus may include besides weathering variations, correctionsfor elevation, shot depth, datum plane, and the like.

In FIGURE 13 is shown graphically the relationship of certain variablesutilized in converting from a scale linear in time to one that is linearin depth according to a given time-depth function. Thus, the graph line130 represents the time-depth curve which is desired to approximate bydesign of the template 90. The curve 131 is any assumed relationshipbetween time and depth having a constant slope which is an average valueof the slope of the curve 130 over the range of interest. Thus, theactual depth D corresponding to any time T is the same as the depth Dread from the curve 131 at the time T corrected by adding an incrementAD The bottom portion of FIGURE 13 shows the value of AD as a functionof time which is determined from the plot of curves 130 and 131 in thismanner. It is this curve 132 which has the same shape as the edge of thetemplate 90, shown as the dotted line and cross-hatched portion of thelower part of FIGURE 13, except that due to the particular arrangementof pulleys and anchor point shown, such that the movement of the cord 87is twice that of the roller 84, the deviation AM of the edge of the mask90 from a straight line' is only one-half of AD. As will be obvious,this shaping-of the edge of the template 90 must further take intoaccount the scale factor between the diameter of the film drum 66 andthe cord-winding drum 95. That is, the value of AM must be reduced bythis further factor.

In operation, with the arm 24 in starting position, the field film 20 ismoved to align thetime break with the index.49 and; clamp 22 is closedto grip the film 20. Slit rods 29jare aligned as in FIGURE 6. Theappropriate weathering card 36 for the particular film 20 is inserted intheholder 37. 7 An unexposed length of film 40 is positioned on'theoutside of drum 66 by turning crank 45 and observing counter 44 untilthe just previously exposed filmis wound on reel 42. If necessary, thespread length is set by moving carriage 110, and its position relativeto the, shot point is set by unlocking lever 107 and appropriatelyshiiting tubular frame 103, 104-, etc. '--Light sou r ce 26 is turned,on, motor 77 is energized, film 20 ismoved around path 21 thereby, andfilm 40 follows at a varying speed depending on the shape of template90, or at a constant speed if the linear time scale is to be retained.Slits 30 move as required to change the positions of relative scanningof the various traces to compensate for normal move-out, so that thetiming of events on all traces is as if the seismometers were alllocated at the shot point. Subsequent records with the same spreadconfiguration are transcribed merely by shifting the field film Z0,winding an unexposed length of film 40 into position, and inserting theproper new weathering card 36 in holder 37 After all records have beentranscribed or the supply of film 40 on reel 43 has been exhausted, theexposed film on reel 42 is removed and developed. After processing anddrying, the corrected records are cut apart and placed side by side,aligned on the basis of zero time or any other desired datum, to formthe record cross section, or a negative from which such a cross sectioncan be photographically printed.

While our invention has been described with reference to the foregoingembodiments and specific details thereof, it is to be understood thatthese are for purposes of illustration only and that the scope of theinvention should not be considered as'limited to these details but isprop erly to be ascertained from the scope of the appended claims.

We claim:

1. A channelized-record transcribing system, for use with a photographicrecord carrying a plurality of channelized substantially parallel traceseach indicative of a recorded seismic signal, comprising means formoving said record along a prescribed path parallel to said traces,means for simultaneously moving a photosensitive film strip along asecond corresponding prescribed path, a stationary optical system atleast in part between said paths adapted to project a small part of thetraces of said record onto said strip, said optical system comprising alight source and means adjacent thereto for forming light from saidsource into a beam of parallel rays of substantial area, a plurality ofslit-carrying members extending across said parallel-ray beam betweensaid film and said beam-forming means, said members being movablesubstantially along the direction of motion of said record, and saidslits being perpendicular to said direction and within said area, meansspaced from said strip for focusing on said strip the portions of saidparallel-ray beam passing through different ones of said slits todifferent parts of said strip along a single straight line transverse tothe direction of motion of said strip, means for moving said membersrelative to each other by amounts adapted to compensate for the normalmove-out of seismic signals recorded on said record, adjustablebeam-deflecting means between said focusing means and said strip, andmeans for individually adjusting said deflecting means to displace fromsaid line in the direction of motion of said strip the position ofincidence thereon of the beam from each of said slits by an amountsufficient to compensate for thettime differences between events on thecorresponding trace and on a reference trace.

2. A system as set forth in claim 1 wherein said defleeting meanscomprisesa pivoted movable mirror, and said adjusting means comprises alever arm, a weathering card, and a holderfor said card adapted to holdthe edge of said card against, and, thereby position, said lever.

3. A channelized-record transcribing systempomprising an outer circulartrack, an inner circular track, means for moving a photographic recordaround one of said tracks, said record carrying'a plurality ofchannelized substantially parallel traces each indicative of a recordedseismic signal, means for moving a photosensitive film strip around theother of said tracks, a stationary optical system at leastimpart-between said tracks adapted to project the traces of said recordonto said strip, said optical system comprising a light source and meansfor forming light from said source into a beam of parallel rays ofsubstantial area, a plurality of slit-carrying members extending acrosssaid parallel-ray beam between said film and said beam-forming means,said members being movable substantially tangent to the direction ofmotion of said record, and said slits being perpendicular to saiddirection and within said area, means spaced from said strip forfocusing on said strip the portions of said parallel-ray beam passingthrough different ones of said slits to different parts of said stripalong a single straight line transverse to the direction of motion ofsaid strip, and means for moving said members relative to each other byamounts adapted to compensate for the normal moveout of seismic signalsrecorded on said record.

4. A system as set forth in claim 3 wherein said slitcarryingmember-moving means comprises a cam of radius varying proportionately toDV where D and V are respectively the depth and average velocity to saiddepth of a given time-depth function, means for rotating said cam indirect proportion to the movement of said record, a follower in contactwith the edge of said cam, and means for transmitting a fractional partof the motion of said follower to said slitcarrying members, saidfractional part varying approximately in proportion to the square of thedistance be- 6. A system as in claim Sincluding means foradjust- 1 ablychanging the position of said point alongsaid lever in proportion to thedistance between said shot point and I the seismorneter farthesttherefrom.

'7. A system as in claim 5 including means for positioning said leafspring and the motion-transmitting means coupled thereto so that theslit-carrying member corresponding to the seismometer nearest said shotpoint is nearest the center of said spring.

References Cited in the file of this patent UNITED STATES PATENTS2,051,153 Rieber Aug. 18, 1936 2,821,892 Merten Feb. 4, 1958 2,825,885Reynolds Mar. 4, 1958 2,861,507 Palmer Nov. 25, 1958

